D2D communication is a technology directly performing communication under the control of a base station and permitting multiplexing cell resources or D2D specific resources between terminals, which is able to increase spectral efficiency of a cellular communication system, lower transmission power of a terminal, and solve the problem that a radio communication system of lack of spectral resources to a certain extent. The D2D technology may be applied to a mobile cellular network, so as to increase a rate of resource utilization and a network capacity. Resources occupied by each D2D communication link are equal to those occupied by a cellular communication link. D2D communication may obtain frequency resources and transmission power needed in communication under the control of a base station. When it shares radio resources with a cellular network, some interference will be brought.
D2D communication may use the same resources as those used by a cellular cell, and may also use D2D specified resources. A user performing D2D communication is also under the control of a base station. A system base station controls the resources used in the D2D communication and transmission power of the D2D communication, so as to ensure that the interference brought by D2D to existing communication of a cell is in an acceptable range.
However, it was found by the inventors that it often occurs in a D2D scenario that two pieces of UE performing D2D traffic advance in the same direction at an approximate or identical speed, such as two pieces of UE in a vehicle. In such a scenario, handover occurs in UE1 and UE2 almost at the same time. According to an existing specification, as a target base station does not know that UE1 and UE2 can establish D2D communication, the target base station will establish a non-D2D communication manner respectively for UE1 and UE2, and then establish D2D communication for UE1 and UE2 by mode selection, thereby resulting in extra signaling overhead and waste of resources.
It should be noted that the above description of the background art is merely provided for clear and complete explanation of the present application and for easy understanding by those skilled in the art. And it should not be understood that the above technical solution is known to those skilled in the art as it is described in the background of the present application.